The benefits of renewable sources such as solar are known to everyone. However, the challenging part is that the power from these sources is not readily available round-the-clock. Solar energy, for instance, is dependent on the distribution of sunlight and is therefore not a reliable source in many locations, especially at night. To counter this, researchers from Stanford University have come up with an alternative low-cost device that can efficiently generate power at night.
The research led by electrical engineer and physicist, Shanhui Fan shows how a modular, low-cost, off-grid energy source can generate electricity at night. The research findings have been published in the Journal Optics Express.
The study approaches radiative cooling to generate electricity. The technique utilizes the change in temperature produced due to the difference in heat absorbed by the surrounding air and the radiant cooling effect of cold space.
The scientists have theoretically shown how an optimized radiative cooling approach can generate a power of 2.2 Watts per square meter. Moreover, the rooftop unit does not require an external energy source or a battery to run. What’s peculiar is that the energy generated is about 120% times than what has been demonstrated ideally. This energy is adequate to power modular sensors like those used in the security and environmental sectors.
Researcher and co-author of the study, Lingling Fan stated:
Thermoelectric Power Generator To Generate Power At Night
So how will radiative cooling be achieved? A thermoelectric power generator is among the most effective ways to implement radiative cooling for power generation. These devices are capable of converting temperature differences between two terminals into electricity. Primarily, the device consists of a heat source and a heat sink. The heat sink is maintained at a temperature lower than the heat source. This variation induces a direct current flow through the load. The devices utilize thermoelectric materials to produce power. The current generated is DC in nature and can be converted into AC using inverters.
In this research, the scientists focused on improving each step in the power generation to maximize the electricity produced from the rooftop system. The scientists increased energy harvesting, enabling more heat to pass through the device from the surrounding air. They also integrated readily available thermoelectric materials to maximize the performance of the system. Notably, thermoelectric power generators are less efficient compared to other mechanical generators. The scientists are working on this and optimizing the device for the best performance. They were able to determine that the best compromise between heat loss and thermoelectric conversion could be accomplished with a thermoelectric generator occupying one square meter on the rooftop.
Wei Li, a member of the team, stated:
The study was demonstrated using computer modelling to simulate the design with pragmatic physical parameters. The previous experimental findings were produced accurately, and it was showcased that this optimized system was capable of achieving what is expected to be the maximum performance using thermoelectric power generators.
Till now, the system is doing wonders for night-time power generation. The researchers are currently carrying out additional experiments for optimizing the device to adapt to day-time power generation as well. If successful, this system could extend the practical applications and revolutionize the round-the-clock (RTC) power supply, which is difficult to achieve with renewable sources of energy such as wind and solar. It is expected that the system will be useful in generating electricity in developing countries.